1. Field of the Invention
The invention relates to an airbag apparatus which is provided in a vehicle, and in which an airbag is deployed ahead of an occupant, for example, when a vehicle is rapidly decelerated.
2. Description of the Related Art
In an airbag of an airbag apparatus described in Japanese Patent Application Publication No. 2004-155420 (JP-A-2004-155420), a cylindrical tube is provided in a manner such that a distal end of the tube is positioned inside the airbag. Further, the distal end of the tube is held by, for example, a clamp. Even when the airbag is in an inflated and deployed state, the tube remains positioned inside the airbag. When the tube is held inside the airbag that is in the inflated and deployed state, the tube remains flattened by the pressure of gas in the airbag.
If the clamp releases the tube when the airbag is in the inflated and deployed state, the tube protrudes to the outside of the airbag due to the pressure in the airbag. Further, the tube is inflated by the pressure of the gas in the airbag. When the airbag apparatus is in this state, the gas in the airbag flows from a proximal end to the distal end of the tube, and the gas is discharged to the outside of the airbag. Thus, the pressure of the gas in the airbag is adjusted.
In the configuration described in the publication No. 2004-155420, when the distal end of the tube is held in the airbag, the tube is flattened by the pressure of the gas in the airbag. However, the gas in the airbag leaks through the tube when the airbag is in an initial inflated deployed state (that is, during a period from when the airbag starts to be inflated and deployed until when the airbag is sufficiently inflated and deployed). Therefore, the size of a gas generator that supplies the gas into the airbag, such as an inflator, needs to be increased to quickly inflate and deploy the airbag.
Also, in the configuration described in the publication No. 2004-155420, when the tube, which has been in the airbag, protrudes to the outside of the airbag, the tube is gradually reversed from the proximal end portion (that is, the tube is turned inside out so that a portion, which has been the inner periphery of the tube, is changed to the outer periphery of the tube, and a portion, which has been the outer periphery of the tube, is changed to the inner periphery of the tube). Therefore, when a timing, at which the tube is released in the airbag, is set, it is necessary to take into account a time required to reverse the tube. This makes it difficult to set the timing at which the tube is released.